Insulator



Oct. 1, 1929. N. A. WAHLBERG INSULATOR Filed May 11, 1927 INVENTOR NilsA.Wahlberg ATTORNEY WITNESSES:

Patented Oct. 1, 1929 UNITED STATES PATENT OFFICE NILS A. WAHLBEBG, OIWILKINSBUBG, PENNSYLVANIA, ASSIGNOR '10 WESTING- HOUSE ELECTRIC 8:MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VANIA nvsumrronApplication filed Kay 11, 1927. Serial 110. 190,417.

My invention relates to insulators and particularly to high-voltagetransmission-line insulators. v

One object of my invention is to'provide an insulator, of theabove-indicated character, that shall embody a reinforcing or holdingmember of such construction and disposition relative to an insulatingmember and a metal terminal member therefor, as to permit the latter to-b constructed of cast metal, such as'aluminum.

Another object of my invention is to provide an insulator terminalstructure, embodyinga wall or sheet portion of relatively great expanse,that shall be effectively braced and reinforced, at its position ofmounting, to prevent tilting thereof relative to the insulator and thatshall be otherwise constructed to maintain the same rigid.

Another object of my invention is to provide an insulator embodying aninsulating column unit free of extensive lateral projectionsintermediate its ends and readily removable terminal units therefor,including annular electrostatic-field-control portions of relativelygreat diameters in which the disassembled column and terminal units of aeffective cementing cooperation between tension elements, such asporcelain and aluminum, which are ordinarily not readily adapted forsuch cooperation.

Another object of my invention is.to provide aninsulator that shallembody upper and lower elements for causing an annular, and widelydistributed, electrostatic field of greatest intensity around, andspaced from,

the insulator within the outer perimeters of the elements, in which thelower element is imperforate and capable of shedding rain.

A further object of myinvention is to provide a high-voltage insulatorstructure that shall be simple and durable in construction, economicalto manufacture and effective in its operation.

In a copending application, Serial No. 548,818, filed April 1, 1922, byH. B. Smith and assigned to the Westinghouse Electric and ManufacturingCompany, is set'forth an insulator of which this invention is animprovement, and to which application reference may be had for a betterunderstanding of the present invention. In general, the insulatoroperates on the principle of both widely distributing the electrostaticfield and causing it to assume the form of a'hollow cylinder, in thesense that the walls of the cylinder are comparatively thick and of lowintensity and the center of the cylinder, next to the insulatingsurface, is of negligible intensity.

This principle requires the use of terminals orelectrostatic-stressdistributing members of relatively great area, whichit is desirable should be as light in weight, and as strong, aspossible.

To obtain these features, it. has heretofore been suggested to constructthe terminals of spun or pressed sheet metal, such as copper, or to makethem of insulating material with a foilor other metal coating.

Also, by reason of the peculiar configuration of the insulatorconstructed of a column that is free of extensive lateral projectionsintermediate its ends and is provided with end toroids or terminals ofrelatively great diameter, the shipment thereof in an economical,effective and safe manner becomes a problem of appreciable concern.

In view of the importance of the art to which the invention relates, andthe particularly arduous service for which the insulator is intended,every feature of operativeness, strength and economy must receivecareful consideration, and it is to this end that the present inventionis proposed.

In practicing m invention, I provide electrostatic-stress- 'stributingand directing terminals that, while of relatively thin sheet formation,are constructed by casting and are so formed and reinforced at aposition of greatest mechanical stress, as to prevent'tilting or bendingof the parts, relative to the insulator and to each other. Thesefeatures permit the use of a very lightweight material, such asaluminum, in a manner to permit it to be effectively cemented toporcelain and to provide an insulator that retains its parts in accuraterelation to each other and is, in general, a marked improvement overprior suggestions.

Also, the insulator is so constructed of readily detachable insulatingcolumn and metal terminal units that, in shipping large numbers ofsimilar insulators, the upper terminals may be nested one withinanother, the columns may be packed in relatively close parallel relationand the lower terminals may be stacked or nested, thus conserving spaceand expense and rendering the shipping operation safer and moreexpeditious.

Figure 1 .of the accompanying drawings,

is a view, partially in elevation and partially in section, of aninsulator constructed in accordance with my invention, and

Fig. 2 is a similar View of a modified form thereof.

Referring to Fig. 1, the device comprises, in general, an insulatingcolumn rod or tube 2, an upper terminal structure 3 and a-lower terminalstructure 4.

The tube or rod 2 is preferably constructed of refractory material, suchas porcelain or glass, although impregnated wood, paper, cloth or anyother suitable material may be employed.

If of porcelain or smiliar material, the

' cylindrical end portion of the rod may be sanded or otherwiseroughened or prepared for effective holding cooperation with cement and,if of glass, the ends may be etched, serrated or otherwise treated forsuch purpose. In the structure illustrated, the tube 2 is of porcelainhaving sanded ends to which are permanently secured or cemented metalclosure cap or cup members 6 and 7, constituing elements of the upperand lower terminals 3 and 4, respectively. These caps are preferably ofdrop-forged iron which is of known strength and ability for effectiveholding cooperation with Portland cement.

The caps are also preferably ungalvanized, particularly on the innersurfaces next to the cement, but may be galvanized on the outer surfacesthereof.

The upper terminal structure 3 further comprises a relatively extensivecombined hood and holding member 8 having parts 10, 11, 12, 14, 15 and16 all integrally united as one homogeneous unit and each having aparticular function cooperating with the others.

The part'10 is a holding clevis, for which a ball or a socket of aball-and-socket connector or other suitable device may be subeted orotherwise connected to provide better a holding cooperation therebetweenthan might be effected directly between the cement and the cap 11 which.is preferably of aluminum. However, the screw-threaded arrangementshown, or other arrangement whereby the member 8 may be readilyremoved-from the tube or column 2, is preferred.

The part 12 is of relatively deep bowl shape and merges very gradually,through the widely-curved portion 14, into the portion 15. The latter isin the form of a relatively wide band or rim about the bowl portion 12and, in contradistinction to the part 12, is of considerably less, oronly slight, in clination to the horizontalor to a line normal to thelongitudinal axis of the rod 2.

The portion 16, in theform of an annular head or rib, serves the doublefunction of water-drip portion and reinforcement against radial crushingor bending.

The part 12 is also, preferably jointed to .the cap 11 by a thickened,and graduallycurved, portion 18 in the position at which exists thegreatest tendency for the other relatively expansive parts to pivot orbend out of true relation to the insulator axis.

The lower terminal structure 4 further comprises a cap portion 20 and aneye portion 21, similar to the cap and clevis portions 11 and 10,respectively, and for similar attachment to the cap or cylinder 7, and

a hood or toroidal portion 22. The latter,

similarly to the upper terminal structure 3, has a portion 24 ofsheet-like formation joined to the cap 20 by a thickened and curvedportion 25 and a combined waterdrip and reinforcing annular bead or rib26. In the above-described structure, a line :12 marks the position ofgreatest electrostaticfield intensity, and although referred to as ofgreatest intensity is in reality of greatly reduced intensity comparedto insulators of other types. In other words, in any insulator theremust be a position or zone of ultimate arc-over and, in-this instance,this zone is caused to be as weak as possible in order to get the fullinsulating value of the. materials employed.

The terminal parts adjacent to this zone,- which is annular orcylindrical in form about the longitudinal axis of the rod 2, re-

cede longitudinally. and radially therefrom so that, at a positionadjacent to the surface of the rod 2 and at a position adjacent to thewater-drip portions 16 and 26, the field is almost negligible instrength.

These features reduce surface current formation alon the rod and preventthe introduction o conducting rain water into the field at a place wherebreakdown of the field might result therefrom.

In suggestions heretofore made, and as shown in Fig. 2 hereof, the lowerterminal 4 has been depressed, or hollowed out, at its upper centralportion adjacent .to the rod 2, but, in thisinstance, the dimensions areso chosen as to obtain substantially the effect of the hollowedterminal. This feature may be seen by taking the upper end of the linea: as a pivot point and swinging the lower end of the line left andright as viewed in the drawing. If this be done, it is seen that thelower end of the line a:, as shown, is at substantially its shortesttouching distance on the lower terminal and assures that ultimatearc-over will occur substantially along the line and that the field isweaker on each side thereof.

This feature provides water drainage for the rod and lower terminal,without perforating the lower terminal, and permits a structure ofbetter casting or construction character to be obtained.

In the above described structure, the features of forming the parts, asshown, and casting them as single integral or homogeneous parts ofaluminum or other suitable material, are believed to be material stepsin advancing and promoting progress in the important field of increasedcommercial transmission line Voltages, to attain which every eifort'isbeing made.

In the form of my invention shown in Fig. 2, in which correspondingparts are designated by corresponding reference characters, theconstruction is substantially the same, with'the exceptions that thebowl portions 12 of the upper terminal 3 is joined to the cap 11 at alower position thereon and the portion 24 of the lower terminal 4 isdisposed above the cap 20 and requires drainage openings 30. I

In'either form, there are only three readily separable and attachableunits, one of which is the column 2 with the caps or end closure members6 and 7 permanently secured thereto, another of which is the singlehomogeneous member 8, including the pa rts or elements 10, 11, 12, 15,Mind 18,

and the third of which is the single homogeneous member or structure 4,including the elements ,20, 21, 22, 24 and 26.

f Hence, in shipping a plurality of such in smators, the above-mentionedunits 8 may be nested one within another, the units 4 may be similarlynested or stacked and the column units 2, since they haveno appreciablelateral projections intermediate their ends, may be packed or crated inrelatively close parallel relation, thus conserving a very great amountof space and facilitating and economizing the shipping operation to a; I

higlvih egree.

ile I have shown and described particular forms of my invention, changesmay be effected therein without departing from the spirit and scopethereof, as set forth in the appended claims.

I claim as my invention:

1. An insulator comprising an insulating column free of extensivelateral rojections intermediate its ends, metal end members permanentlysecured thereto, an upper electrostatic-field-control hood of relativelygreat diameter compared to the length of. the column readily removablysecured to one of said end members and a lower annular fieldcontrolmember of smaller diameter than the hood readily removably secured tothe other end member, the arrangement of parts permitting shipment of alurality of disassembled similar insulators y nesting the hoods,stacking the lower field-control members and placing the columns inrelatively close parallel relation to each other.

2. An insulator comprising an insulating column free of extensivelateral projectionsintermediate its ends,externally screw-thread edmetal sleeves permanently secured in position around said ends, an upperelectrostatic-field-control hood having an internally-screw-threadedportion for cooperation with one of said sleeves and a lower annularfield-control member of smaller diameter than the hood having aninternally-screw threaded portion for cooperation with the other sleeve.

3. An insulator comprising an insulating column free of extensivelateral projections intermediate its ends, externally screwthreadedmetal sleeves permanently secured in position around said ends, a singlehomogeneous upper member including an electrostatic-field-control hoodportion, an internally-screw-threaded portion for cooperation with oneof said sleeves and a portion for mounting the insulator, and a singlehomogeneous lower member including an annular field-control portion ofsmaller diameter than the hood, an internally-screw-threaded portion forcooperation with the other sleeve and a portion for attaching an objectto the lower end of the column.

4. An insulator comprising a tubular insulating column, metalend-closure members therefor permanently secured thereto, and means forreadily-removable attachment as a unit to each of said end-closuremembers in cluding an electrostatic-field-control portion and a portionfor attaching the insulator to another object.

5. An insulator comprising a tubular insulating column, metalend-closure cups permanently secured in telescopic relation over theends of the column, said cups having exteriorly-screw-threaded sidesurfaces, and

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means for readily-removable attachment as a unit to each of said cu s,the upper of said means'including a hoe portion of relatively greatdiameter compared to the length of the column, aninternally-screw-threaded central sleeve portion and a portion formounting the insulator, and the lower of said means ineluding afield-control torus of smaller diameter than said hood, aninternally-screww threaded central sleeve portion and a portion forattaching an object to the lower end of the column. In testimonywhereof, I have hereunto subscribed my name this 29th day of April,1927. NI LS A. WAHLBERG

